i want make a call on web skype, but failed Rated 1 out of 5 stars

i want make a call on web skype, but failed, because it required an anditional plugin, and i had download the plugin, but can't install it . i don't know why.

This review is for a previous version of the add-on (8.4.0.9160).  This user has a previous review of this add-on.